1/*
2 * Copyright 2006-2019 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the OpenSSL license (the "License").  You may not use
5 * this file except in compliance with the License.  You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10#include <stdio.h>
11#include "internal/cryptlib.h"
12#include <openssl/asn1t.h>
13#include <openssl/x509.h>
14#include <openssl/ec.h>
15#include "ec_local.h"
16#include <openssl/evp.h>
17#include "crypto/evp.h"
18
19/* EC pkey context structure */
20
21typedef struct {
22    /* Key and paramgen group */
23    EC_GROUP *gen_group;
24    /* message digest */
25    const EVP_MD *md;
26    /* Duplicate key if custom cofactor needed */
27    EC_KEY *co_key;
28    /* Cofactor mode */
29    signed char cofactor_mode;
30    /* KDF (if any) to use for ECDH */
31    char kdf_type;
32    /* Message digest to use for key derivation */
33    const EVP_MD *kdf_md;
34    /* User key material */
35    unsigned char *kdf_ukm;
36    size_t kdf_ukmlen;
37    /* KDF output length */
38    size_t kdf_outlen;
39} EC_PKEY_CTX;
40
41static int pkey_ec_init(EVP_PKEY_CTX *ctx)
42{
43    EC_PKEY_CTX *dctx;
44
45    if ((dctx = OPENSSL_zalloc(sizeof(*dctx))) == NULL) {
46        ECerr(EC_F_PKEY_EC_INIT, ERR_R_MALLOC_FAILURE);
47        return 0;
48    }
49
50    dctx->cofactor_mode = -1;
51    dctx->kdf_type = EVP_PKEY_ECDH_KDF_NONE;
52    ctx->data = dctx;
53    return 1;
54}
55
56static int pkey_ec_copy(EVP_PKEY_CTX *dst, EVP_PKEY_CTX *src)
57{
58    EC_PKEY_CTX *dctx, *sctx;
59    if (!pkey_ec_init(dst))
60        return 0;
61    sctx = src->data;
62    dctx = dst->data;
63    if (sctx->gen_group) {
64        dctx->gen_group = EC_GROUP_dup(sctx->gen_group);
65        if (!dctx->gen_group)
66            return 0;
67    }
68    dctx->md = sctx->md;
69
70    if (sctx->co_key) {
71        dctx->co_key = EC_KEY_dup(sctx->co_key);
72        if (!dctx->co_key)
73            return 0;
74    }
75    dctx->kdf_type = sctx->kdf_type;
76    dctx->kdf_md = sctx->kdf_md;
77    dctx->kdf_outlen = sctx->kdf_outlen;
78    if (sctx->kdf_ukm) {
79        dctx->kdf_ukm = OPENSSL_memdup(sctx->kdf_ukm, sctx->kdf_ukmlen);
80        if (!dctx->kdf_ukm)
81            return 0;
82    } else
83        dctx->kdf_ukm = NULL;
84    dctx->kdf_ukmlen = sctx->kdf_ukmlen;
85    return 1;
86}
87
88static void pkey_ec_cleanup(EVP_PKEY_CTX *ctx)
89{
90    EC_PKEY_CTX *dctx = ctx->data;
91    if (dctx != NULL) {
92        EC_GROUP_free(dctx->gen_group);
93        EC_KEY_free(dctx->co_key);
94        OPENSSL_free(dctx->kdf_ukm);
95        OPENSSL_free(dctx);
96        ctx->data = NULL;
97    }
98}
99
100static int pkey_ec_sign(EVP_PKEY_CTX *ctx, unsigned char *sig, size_t *siglen,
101                        const unsigned char *tbs, size_t tbslen)
102{
103    int ret, type;
104    unsigned int sltmp;
105    EC_PKEY_CTX *dctx = ctx->data;
106    EC_KEY *ec = ctx->pkey->pkey.ec;
107    const int sig_sz = ECDSA_size(ec);
108
109    /* ensure cast to size_t is safe */
110    if (!ossl_assert(sig_sz > 0))
111        return 0;
112
113    if (sig == NULL) {
114        *siglen = (size_t)sig_sz;
115        return 1;
116    }
117
118    if (*siglen < (size_t)sig_sz) {
119        ECerr(EC_F_PKEY_EC_SIGN, EC_R_BUFFER_TOO_SMALL);
120        return 0;
121    }
122
123    type = (dctx->md != NULL) ? EVP_MD_type(dctx->md) : NID_sha1;
124
125    ret = ECDSA_sign(type, tbs, tbslen, sig, &sltmp, ec);
126
127    if (ret <= 0)
128        return ret;
129    *siglen = (size_t)sltmp;
130    return 1;
131}
132
133static int pkey_ec_verify(EVP_PKEY_CTX *ctx,
134                          const unsigned char *sig, size_t siglen,
135                          const unsigned char *tbs, size_t tbslen)
136{
137    int ret, type;
138    EC_PKEY_CTX *dctx = ctx->data;
139    EC_KEY *ec = ctx->pkey->pkey.ec;
140
141    if (dctx->md)
142        type = EVP_MD_type(dctx->md);
143    else
144        type = NID_sha1;
145
146    ret = ECDSA_verify(type, tbs, tbslen, sig, siglen, ec);
147
148    return ret;
149}
150
151#ifndef OPENSSL_NO_EC
152static int pkey_ec_derive(EVP_PKEY_CTX *ctx, unsigned char *key, size_t *keylen)
153{
154    int ret;
155    size_t outlen;
156    const EC_POINT *pubkey = NULL;
157    EC_KEY *eckey;
158    EC_PKEY_CTX *dctx = ctx->data;
159    if (!ctx->pkey || !ctx->peerkey) {
160        ECerr(EC_F_PKEY_EC_DERIVE, EC_R_KEYS_NOT_SET);
161        return 0;
162    }
163
164    eckey = dctx->co_key ? dctx->co_key : ctx->pkey->pkey.ec;
165
166    if (!key) {
167        const EC_GROUP *group;
168        group = EC_KEY_get0_group(eckey);
169        *keylen = (EC_GROUP_get_degree(group) + 7) / 8;
170        return 1;
171    }
172    pubkey = EC_KEY_get0_public_key(ctx->peerkey->pkey.ec);
173
174    /*
175     * NB: unlike PKCS#3 DH, if *outlen is less than maximum size this is not
176     * an error, the result is truncated.
177     */
178
179    outlen = *keylen;
180
181    ret = ECDH_compute_key(key, outlen, pubkey, eckey, 0);
182    if (ret <= 0)
183        return 0;
184    *keylen = ret;
185    return 1;
186}
187
188static int pkey_ec_kdf_derive(EVP_PKEY_CTX *ctx,
189                              unsigned char *key, size_t *keylen)
190{
191    EC_PKEY_CTX *dctx = ctx->data;
192    unsigned char *ktmp = NULL;
193    size_t ktmplen;
194    int rv = 0;
195    if (dctx->kdf_type == EVP_PKEY_ECDH_KDF_NONE)
196        return pkey_ec_derive(ctx, key, keylen);
197    if (!key) {
198        *keylen = dctx->kdf_outlen;
199        return 1;
200    }
201    if (*keylen != dctx->kdf_outlen)
202        return 0;
203    if (!pkey_ec_derive(ctx, NULL, &ktmplen))
204        return 0;
205    if ((ktmp = OPENSSL_malloc(ktmplen)) == NULL) {
206        ECerr(EC_F_PKEY_EC_KDF_DERIVE, ERR_R_MALLOC_FAILURE);
207        return 0;
208    }
209    if (!pkey_ec_derive(ctx, ktmp, &ktmplen))
210        goto err;
211    /* Do KDF stuff */
212    if (!ecdh_KDF_X9_63(key, *keylen, ktmp, ktmplen,
213                        dctx->kdf_ukm, dctx->kdf_ukmlen, dctx->kdf_md))
214        goto err;
215    rv = 1;
216
217 err:
218    OPENSSL_clear_free(ktmp, ktmplen);
219    return rv;
220}
221#endif
222
223static int pkey_ec_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
224{
225    EC_PKEY_CTX *dctx = ctx->data;
226    EC_GROUP *group;
227    switch (type) {
228    case EVP_PKEY_CTRL_EC_PARAMGEN_CURVE_NID:
229        group = EC_GROUP_new_by_curve_name(p1);
230        if (group == NULL) {
231            ECerr(EC_F_PKEY_EC_CTRL, EC_R_INVALID_CURVE);
232            return 0;
233        }
234        EC_GROUP_free(dctx->gen_group);
235        dctx->gen_group = group;
236        return 1;
237
238    case EVP_PKEY_CTRL_EC_PARAM_ENC:
239        if (!dctx->gen_group) {
240            ECerr(EC_F_PKEY_EC_CTRL, EC_R_NO_PARAMETERS_SET);
241            return 0;
242        }
243        EC_GROUP_set_asn1_flag(dctx->gen_group, p1);
244        return 1;
245
246#ifndef OPENSSL_NO_EC
247    case EVP_PKEY_CTRL_EC_ECDH_COFACTOR:
248        if (p1 == -2) {
249            if (dctx->cofactor_mode != -1)
250                return dctx->cofactor_mode;
251            else {
252                EC_KEY *ec_key = ctx->pkey->pkey.ec;
253                return EC_KEY_get_flags(ec_key) & EC_FLAG_COFACTOR_ECDH ? 1 : 0;
254            }
255        } else if (p1 < -1 || p1 > 1)
256            return -2;
257        dctx->cofactor_mode = p1;
258        if (p1 != -1) {
259            EC_KEY *ec_key = ctx->pkey->pkey.ec;
260            if (!ec_key->group)
261                return -2;
262            /* If cofactor is 1 cofactor mode does nothing */
263            if (BN_is_one(ec_key->group->cofactor))
264                return 1;
265            if (!dctx->co_key) {
266                dctx->co_key = EC_KEY_dup(ec_key);
267                if (!dctx->co_key)
268                    return 0;
269            }
270            if (p1)
271                EC_KEY_set_flags(dctx->co_key, EC_FLAG_COFACTOR_ECDH);
272            else
273                EC_KEY_clear_flags(dctx->co_key, EC_FLAG_COFACTOR_ECDH);
274        } else {
275            EC_KEY_free(dctx->co_key);
276            dctx->co_key = NULL;
277        }
278        return 1;
279#endif
280
281    case EVP_PKEY_CTRL_EC_KDF_TYPE:
282        if (p1 == -2)
283            return dctx->kdf_type;
284        if (p1 != EVP_PKEY_ECDH_KDF_NONE && p1 != EVP_PKEY_ECDH_KDF_X9_63)
285            return -2;
286        dctx->kdf_type = p1;
287        return 1;
288
289    case EVP_PKEY_CTRL_EC_KDF_MD:
290        dctx->kdf_md = p2;
291        return 1;
292
293    case EVP_PKEY_CTRL_GET_EC_KDF_MD:
294        *(const EVP_MD **)p2 = dctx->kdf_md;
295        return 1;
296
297    case EVP_PKEY_CTRL_EC_KDF_OUTLEN:
298        if (p1 <= 0)
299            return -2;
300        dctx->kdf_outlen = (size_t)p1;
301        return 1;
302
303    case EVP_PKEY_CTRL_GET_EC_KDF_OUTLEN:
304        *(int *)p2 = dctx->kdf_outlen;
305        return 1;
306
307    case EVP_PKEY_CTRL_EC_KDF_UKM:
308        OPENSSL_free(dctx->kdf_ukm);
309        dctx->kdf_ukm = p2;
310        if (p2)
311            dctx->kdf_ukmlen = p1;
312        else
313            dctx->kdf_ukmlen = 0;
314        return 1;
315
316    case EVP_PKEY_CTRL_GET_EC_KDF_UKM:
317        *(unsigned char **)p2 = dctx->kdf_ukm;
318        return dctx->kdf_ukmlen;
319
320    case EVP_PKEY_CTRL_MD:
321        if (EVP_MD_type((const EVP_MD *)p2) != NID_sha1 &&
322            EVP_MD_type((const EVP_MD *)p2) != NID_ecdsa_with_SHA1 &&
323            EVP_MD_type((const EVP_MD *)p2) != NID_sha224 &&
324            EVP_MD_type((const EVP_MD *)p2) != NID_sha256 &&
325            EVP_MD_type((const EVP_MD *)p2) != NID_sha384 &&
326            EVP_MD_type((const EVP_MD *)p2) != NID_sha512 &&
327            EVP_MD_type((const EVP_MD *)p2) != NID_sha3_224 &&
328            EVP_MD_type((const EVP_MD *)p2) != NID_sha3_256 &&
329            EVP_MD_type((const EVP_MD *)p2) != NID_sha3_384 &&
330            EVP_MD_type((const EVP_MD *)p2) != NID_sha3_512) {
331            ECerr(EC_F_PKEY_EC_CTRL, EC_R_INVALID_DIGEST_TYPE);
332            return 0;
333        }
334        dctx->md = p2;
335        return 1;
336
337    case EVP_PKEY_CTRL_GET_MD:
338        *(const EVP_MD **)p2 = dctx->md;
339        return 1;
340
341    case EVP_PKEY_CTRL_PEER_KEY:
342        /* Default behaviour is OK */
343    case EVP_PKEY_CTRL_DIGESTINIT:
344    case EVP_PKEY_CTRL_PKCS7_SIGN:
345    case EVP_PKEY_CTRL_CMS_SIGN:
346        return 1;
347
348    default:
349        return -2;
350
351    }
352}
353
354static int pkey_ec_ctrl_str(EVP_PKEY_CTX *ctx,
355                            const char *type, const char *value)
356{
357    if (strcmp(type, "ec_paramgen_curve") == 0) {
358        int nid;
359        nid = EC_curve_nist2nid(value);
360        if (nid == NID_undef)
361            nid = OBJ_sn2nid(value);
362        if (nid == NID_undef)
363            nid = OBJ_ln2nid(value);
364        if (nid == NID_undef) {
365            ECerr(EC_F_PKEY_EC_CTRL_STR, EC_R_INVALID_CURVE);
366            return 0;
367        }
368        return EVP_PKEY_CTX_set_ec_paramgen_curve_nid(ctx, nid);
369    } else if (strcmp(type, "ec_param_enc") == 0) {
370        int param_enc;
371        if (strcmp(value, "explicit") == 0)
372            param_enc = 0;
373        else if (strcmp(value, "named_curve") == 0)
374            param_enc = OPENSSL_EC_NAMED_CURVE;
375        else
376            return -2;
377        return EVP_PKEY_CTX_set_ec_param_enc(ctx, param_enc);
378    } else if (strcmp(type, "ecdh_kdf_md") == 0) {
379        const EVP_MD *md;
380        if ((md = EVP_get_digestbyname(value)) == NULL) {
381            ECerr(EC_F_PKEY_EC_CTRL_STR, EC_R_INVALID_DIGEST);
382            return 0;
383        }
384        return EVP_PKEY_CTX_set_ecdh_kdf_md(ctx, md);
385    } else if (strcmp(type, "ecdh_cofactor_mode") == 0) {
386        int co_mode;
387        co_mode = atoi(value);
388        return EVP_PKEY_CTX_set_ecdh_cofactor_mode(ctx, co_mode);
389    }
390
391    return -2;
392}
393
394static int pkey_ec_paramgen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
395{
396    EC_KEY *ec = NULL;
397    EC_PKEY_CTX *dctx = ctx->data;
398    int ret;
399
400    if (dctx->gen_group == NULL) {
401        ECerr(EC_F_PKEY_EC_PARAMGEN, EC_R_NO_PARAMETERS_SET);
402        return 0;
403    }
404    ec = EC_KEY_new();
405    if (ec == NULL)
406        return 0;
407    if (!(ret = EC_KEY_set_group(ec, dctx->gen_group))
408        || !ossl_assert(ret = EVP_PKEY_assign_EC_KEY(pkey, ec)))
409        EC_KEY_free(ec);
410    return ret;
411}
412
413static int pkey_ec_keygen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
414{
415    EC_KEY *ec = NULL;
416    EC_PKEY_CTX *dctx = ctx->data;
417    int ret;
418
419    if (ctx->pkey == NULL && dctx->gen_group == NULL) {
420        ECerr(EC_F_PKEY_EC_KEYGEN, EC_R_NO_PARAMETERS_SET);
421        return 0;
422    }
423    ec = EC_KEY_new();
424    if (ec == NULL)
425        return 0;
426    if (!ossl_assert(EVP_PKEY_assign_EC_KEY(pkey, ec))) {
427        EC_KEY_free(ec);
428        return 0;
429    }
430    /* Note: if error is returned, we count on caller to free pkey->pkey.ec */
431    if (ctx->pkey != NULL)
432        ret = EVP_PKEY_copy_parameters(pkey, ctx->pkey);
433    else
434        ret = EC_KEY_set_group(ec, dctx->gen_group);
435
436    return ret ? EC_KEY_generate_key(ec) : 0;
437}
438
439const EVP_PKEY_METHOD ec_pkey_meth = {
440    EVP_PKEY_EC,
441    0,
442    pkey_ec_init,
443    pkey_ec_copy,
444    pkey_ec_cleanup,
445
446    0,
447    pkey_ec_paramgen,
448
449    0,
450    pkey_ec_keygen,
451
452    0,
453    pkey_ec_sign,
454
455    0,
456    pkey_ec_verify,
457
458    0, 0,
459
460    0, 0, 0, 0,
461
462    0,
463    0,
464
465    0,
466    0,
467
468    0,
469#ifndef OPENSSL_NO_EC
470    pkey_ec_kdf_derive,
471#else
472    0,
473#endif
474    pkey_ec_ctrl,
475    pkey_ec_ctrl_str
476};
477